Method and apparatus for improving the operation of a dust collector

Abstract

The invention provides a dust collector for use in air pollution control which includes at least one hollow filter assembly disposed in a hopper and having an open upper end registering with a wall opening. The filter apparatus also includes a nozzle spaced above the filter assembly for selectively directing a reverse pulse of air into the open upper end of the filter such that the reverse air pulse enters the filter assembly and flows through the filter medium in the reverse of the direction of contaminated airflow to thereby remove accumulated contaminants from the filter medium. The dust collector further includes a sleeve positioned inside the hollow filter assembly with the outer surface of the sleeve adjacent the filter medium, the upper end of the sleeve registering with the wall opening and the lower end of the sleeve opening into the filter assembly.

I claim: 
     
       1. A dust collector comprising, in combination, a hopper,   an exhaust chamber,   a wall separating said hopper and said exhaust chamber, said wall including an opening having a diameter,   means for filtering contaminated air flowing through said opening from said hopper, said filtering means including a hollow fitler assembly comprising filter medium and having upper and lower ends, said upper end of said filter assembly registering with said wall opening, said hopper being generally sealed from said exhaust chamber except through said wall opening and said filter medium of said filter assembly, and said filtering means further including means for supporting said filter assembly and for sealing said lower end of said filter assembly, said supporting and sealing means copmrising an end plate generally parallel to said wall and at said lower end of said filter assembly,   means defining an inlet into said hopper for introducing contaminated air into said hopper so that said contaminated air is caused to flow to said exhaust chamber through said filter medium and airborne contaminants are accumulated on said filter medium,   means for selectively directing reverse pulses of air into said wall opening from said exhaust chamber whereby said reverse air pulses enter said filter assembly and generate airflow through said filter medium in the reverse of the direction of contaminated airflow to remove accumulated contaminants from said filter medium, said air pulse directing means including nozzle means spaced above said wall opening, said nozzle means being constructred to accelerate the air emitted toward said wall opening such that said air pulses are emitted from said nozzle means and propagate toward said wall opening in a cone-shaped pattern and enter said wall opening, and   means for reducing the velocity of said reverse air pulses and for preventing said reverse air pulses from impinging upon said filter medium as said reverse air pulses propagate to said lower end of said hollow filter assembly, said reducing and preventing means including an air impermeable sleeve having upper and lower ends, an outer surface and an inner cylindrical surface, and an outside diameter substantially equal to said diameter of said wall opening, said sleeve being positioned inside said hollow filter assembly with said outer surface closely adjacent but spaced from said filter medium, and with said upper end of said sleeve registering with said wall opening and said lower end of said sleeve opening into said filter assembly, said sleeve extending into said filter assembly a substantial distance and with the lower end thereof being spaced from said nozzle means a preselected distance to insure that air pulse cone-shaped pattern impinges on said inner surface of said sleeve, said preselected distance also being such that the velocity of said air pulses emitted from said lower end of said sleeve is reduced sufficiently as compared to the velocity of said air pulses at said opening so that said air pulses emitted from said lower end of said sleeve do not grow by drawing air through said filter medium so as to impinge upon said filter medium as said air pulses propagate from said lower end of said sleeve to said lower end of said hollow filter assembly but impinge directly on said end plate.   
     
     
       2. A dust collector as set forth in claim 1 wherein said air pulses exit said lower end of said sleeve at a speed of 150 to 250 feet per second. 
     
     
       3. A dust collector as set forth in claim 1 wherein said means for directing a reverse pulse of air includes a conduit in said exhaust chamber and means for supplying air under pressure to said conduit, and wherein said nozzle is supported by said conduit and directs air from said conduit toward said opening. 
     
     
       4. A dust collector as set forth in claim 1 wherein said nozzle means accelerates the air emitted toward said wall opening to supersonic velocity. 
     
     
       5. A dust collector as set forth in claim 4 wherein said air pulses exit said lower end of said sleeve at a speed of 150 to 250 feet per second.